In a liquid crystal display device, a TFT substrate in which pixel electrodes, thin film transistors (TFTs), and the like, are formed in matrix, is disposed facing a color filter substrate in which color filters, and the like are formed at positions corresponding to the pixel electrodes of the TFT substrate. There is provided a liquid crystal between the TFT substrate and the color filter substrate. The liquid crystal display device controls the transmittance of light of the liquid crystal molecules for each pixel to form an image.
The liquid crystal display device can have a flat screen and a reduced thickness, allowing it to be used in a wide range of applications including small display devices such as mobile phone and digital still camera (DSC), as well as large display device such as TV. In general, the liquid crystal display device for TV uses a direct-type backlight with a cold cathode fluorescent lamp (CFL), which is a light source, provided under a liquid crystal display panel.
The direct-type backlight can easily increase the screen brightness. However, the provision of the direct-type backlight increases the thickness of the liquid crystal display device. In order to reduce the thickness of the liquid crystal display device, it is possible to use a backlight of a side light system in which cold cathode fluorescent lamps are provided on the sides of a light guide panel constituting the backlight of the liquid crystal display device.
Examples of such a liquid crystal display device using the side light system that provides cold cathode fluorescent lamps on the sides of the light guide panel, can be found in JP-A No. 126523/2001, JP-A No. 10789/2006, and JP-A 151922/1995. JP-A No. 126523/2001 describes a configuration of the side light system that provides cold cathode fluorescent lamps on the four sides of the light guide panel while stabilizing the position of the light guide panel in a housing member, for example, formed by a mold (hereinafter the housing member will be referred to as “mold”).
JP-A No. 10789/2006 describes a configuration of the side light system that uses a U-shaped cold cathode fluorescent lamp to surround the three sides of the light guide panel. Further, JP-A 151922/1995 describes a configuration of the side light system that uses two L-shaped cold cathode fluorescent lamps to surround the four sides of the light guide panel.
In a liquid crystal display device of side light system with cold cathode fluorescent lamps provided on the sides of a light guide panel, the thickness can be further reduced compared to the thickness of a direct-type liquid crystal display device in which a cold cathode fluorescent lamp is provided under a liquid display panel. However, it is difficult to reduce the thickness enough for applications such as wall-hanging TV. In addition, the use of the cold cathode fluorescent lamps requires an inverter circuit to reduce flicker. However, the weight of the inverter is large, which is an obstacle for applications such as wall-hanging TV.
For example, a 32 inch TV with an existing liquid crystal display device for TV has the thickness of 10 cm, and the weight of about 20 Kg excluding the stand. Thus, in order to hang the TV on a wall, the work similar to that of mounting an air conditioner is necessary.
The present invention aims to provide a thin and lightweight TV that can be hung on a wall without the need of such a large-scale work.